Removal methods for high aspect ratio structures

ABSTRACT

Exemplary cleaning or etching methods may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. Methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a region of exposed oxide. Methods may also include providing a hydrogen-containing precursor to the processing region. The methods may further include removing at least a portion of the exposed oxide while maintaining a relative humidity within the processing region below about 50%. Subsequent to the removal, the methods may include increasing the relative humidity within the processing region to greater than or about 50%. The methods may further include removing an additional amount of the exposed oxide.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment.More specifically, the present technology relates to cleaning or etchinghigh-aspect-ratio structures.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers, or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess that etches one material faster than another facilitating, forexample, a pattern transfer process. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits, and processes, etch processes have been developedwith a selectivity towards a variety of materials.

Etch processes may be termed wet or dry based on the materials used inthe process. A wet HF etch preferentially removes silicon oxide overother dielectrics and materials. However, wet processes may havedifficulty penetrating some constrained trenches and also may sometimesdeform the remaining material. Dry etches produced in local plasmasformed within the substrate processing region can penetrate moreconstrained trenches and exhibit less deformation of delicate remainingstructures. However, local plasmas may damage the substrate through theproduction of electric arcs as they discharge.

Thus, there is a need for improved systems and methods that can be usedto produce high quality devices and structures. These and other needsare addressed by the present technology.

SUMMARY

Exemplary cleaning, removal, and etching methods may include flowing afluorine-containing precursor into a remote plasma region of asemiconductor processing chamber. The methods may include forming aplasma within the remote plasma region to generate plasma effluents ofthe fluorine-containing precursor. The methods may also include flowingthe plasma effluents into a processing region of the semiconductorprocessing chamber. A substrate may be positioned within the processingregion, and the substrate may include a region of exposed oxide. Themethods may also include providing a hydrogen-containing precursor tothe processing region. The methods may further include removing at leasta portion of the exposed oxide while maintaining a relative humiditywithin the processing region below about 50%. Subsequent to the removal,the methods may include increasing the relative humidity within theprocessing region to greater than or about 50%. The methods may furtherinclude removing an additional amount of the exposed oxide.

Exemplary methods may also include continuing to flow the plasmaeffluents into the processing region while increasing the relativehumidity within the processing region. A flow rate of the plasmaeffluents may be reduced while increasing the relative humidity withinthe processing region. In embodiments, a temperature of the substratemay be reduced while increasing the relative humidity within theprocessing region. For example, the temperature may be reduced by atleast about 5° C. In embodiments a pressure within the processingchamber may be increased while increasing the relative humidity withinthe processing region. For example, the pressure may be increased by atleast about 1 Torr. The relative humidity may be increased above about65% in some embodiments. After methods according to the presenttechnology have been performed including removal of an additional amountof exposed oxide, a concentration of fluorine in the substrate may bebelow or about 5%. Similarly, a concentration of oxygen in the substratemay be below or about 8%. In some embodiments, the hydrogen-containingprecursor may bypass the remote plasma region when provided to theprocessing region. In some embodiments, the processing region may bemaintained plasma free during the removing operations. Additionally, therelative humidity may be increased incrementally during exemplarymethods, and may be increased incrementally by less than or about 20%per increment.

The present technology also encompasses cleaning methods. The methodsmay include flowing a fluorine-containing precursor into a remote plasmaregion of a semiconductor processing chamber while forming a plasmawithin the remote plasma region to generate plasma effluents of thefluorine-containing precursor. The methods may include flowing theplasma effluents into a processing region of the semiconductorprocessing chamber. The processing region may house or contain asubstrate that may include a high-aspect-ratio feature having a regionof exposed oxide. While flowing the plasma effluents into the processingregion, the methods may include providing a hydrogen-containingprecursor to the processing region. The methods may include removing atleast a portion of the exposed oxide while maintaining a relativehumidity within the processing region at greater than or about 50%. Themethods may further include, subsequent the removing at least a portionof the exposed oxide, increasing a flow rate of the fluorine-containingprecursor while maintaining the relative humidity within the processingregion at greater than or about 50%. The methods may also includeremoving an additional amount of the exposed oxide.

In embodiments removing an additional amount of the exposed oxide maylower a concentration of oxygen by at least about 5%. In exemplarymethods, the flow rate of the fluorine-containing precursor may beincreased by at least about 2 sccm. In embodiments, a thickness of theexposed region of oxide prior to the removal operations may be less thanor about 2 nm. Additionally, in some embodiments, a critical dimensionof the high-aspect-ratio feature may be reduced by less than or about1%.

The present technology also encompasses removal methods. The methods mayinclude flowing a fluorine-containing precursor into a remote plasmaregion of a semiconductor processing chamber while forming a plasmawithin the remote plasma region to generate plasma effluents of thefluorine-containing precursor. The methods may include flowing theplasma effluents into a processing region of the semiconductorprocessing chamber. The processing region may house a substrate, whichmay have one or more high-aspect-ratio features having a region ofexposed oxide. While flowing the plasma effluents into the processingregion, the methods may include providing a hydrogen-containingprecursor to the processing region. The methods may include continuingto flow the plasma effluents and the hydrogen-containing precursor intothe processing region for at least about 200 seconds. The methods mayalso include removing at least a portion of the exposed oxide whilemaintaining a relative humidity within the processing region at greaterthan or about 50%. In some embodiments, the removing operation mayreduce a surface-level concentration of oxygen within the substrate byat least about 3%.

Such technology may provide numerous benefits over conventional systemsand techniques. For example, the processes may allow high-aspect-ratiofeatures to be etched without developing pattern collapse. Additionally,the processes may allow a material removal to be performed whilelimiting a surface contamination level of a substrate. These and otherembodiments, along with many of their advantages and features, aredescribed in more detail in conjunction with the below description andattached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a top plan view of one embodiment of an exemplaryprocessing system according to embodiments of the present technology.

FIG. 2A shows a schematic cross-sectional view of an exemplaryprocessing chamber according to embodiments of the present technology.

FIG. 2B shows a detailed view of a portion of the processing chamberillustrated in FIG. 2A according to embodiments of the presenttechnology.

FIG. 3 shows a bottom plan view of an exemplary showerhead according toembodiments of the present technology.

FIG. 4 shows exemplary operations in a method according to embodimentsof the present technology.

FIGS. 5A-5C show cross-sectional views of substrates being processedaccording to embodiments of the present technology.

FIG. 6 shows a chart illustrating surface concentrations of elements inrelation to relative humidity according to embodiments of the presenttechnology.

FIG. 7 shows exemplary operations in a method according to embodimentsof the present technology.

FIG. 8 shows a chart illustrating surface concentrations of elements inrelation to precursor flow rate according to embodiments of the presenttechnology.

FIG. 9 shows exemplary operations in a method according to embodimentsof the present technology.

FIG. 10 shows a chart illustrating surface concentrations of elements inrelation to elapsed time according to embodiments of the presenttechnology.

Several of the figures are included as schematics. It is to beunderstood that the figures are for illustrative purposes, and are notto be considered of scale unless specifically stated to be of scale.Additionally, as schematics, the figures are provided to aidcomprehension and may not include all aspects or information compared torealistic representations, and may include additional or exaggeratedmaterial for illustrative purposes.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a letter thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the letter.

DETAILED DESCRIPTION

Diluted acids may be used in many different semiconductor processes forcleaning substrates, and removing materials from those substrates. Forexample, diluted hydrofluoric acid can be an effective etchant forsilicon oxide, and may be used to remove silicon oxide from siliconsurfaces. After the etching or cleaning operation is complete, the acidmay be dried from the wafer or substrate surface. Using dilutehydrofluoric acid (“DHF”) may be termed a “wet” etch, and the diluent isoften water. Water has a relatively high surface tension that may act onthe surfaces with which it is in contact.

Device patterning and features that continue to shrink in dimension mayinclude delicate features etched or formed on a substrate. For example,many processing operations may work upon or form trenches, holes, orother features in a substrate or materials on a substrate. The aspectratio, defined as the height to width ratio, may be very high indevices, and can be on the order of 5, 10, 20, 50, 100 or greater. Manyof these features may have not only high aspect ratios, but also reduceddimensions on the scale of a few nanometers, for example, such that thecritical dimensions across the substrate—often the width or dimension ofthese features—may be less than 10 nm, less than 5 nm, less than 3 nm,less than 2 nm, less than 1 nm, or even smaller. For example, the widthof any particular column or wall between two trenches may be of only afew nanometers. The thinner is this material, the more impact stressesmay pose on the integrity of the structure. Additionally, the materialcomposing the structure may also impact the effect of exerted pressuresor stresses on the material, be it a substrate material, dielectric,photo-resist, etc.

Issues may arise when delicate, high-aspect-ratio features are cleaned,etched, or processed, because the fluids may exhibit surface tensionsthat may be much higher than can be managed by the features. In designshaving multiple features, layers, or materials, even a small amount offeature deformation or collapse can cause short circuits through theproduced device rendering it inoperable. For example, although DHF maywork well on low aspect ratio structures, when used as an etchant onhigh-aspect-ratio features, when the etching operation is finished andthe DHF is dried or removed, the surface tension imposed on the featuresduring the drying may cause pattern collapse. As device featurescontinue to shrink, wet etching may no longer be sufficient because ofits effect on high-aspect-ratio features. One promising technology forfluid removal in cleaning operations is by performing drying operationswith super-critical fluids. Although these techniques may providesurfaces that are drier and less prone to pattern collapse, the amountof preparation, hardware requirements, and the number of operationsinvolved may reduce the efficiency of overall substrate processing.

The present technology overcomes these issues by performing a dry etchprocess that provides adequate selectivity for the removal of siliconoxide relative to silicon, while maintaining high-aspect-ratiostructures. The technology utilizes plasma enhanced precursors, whichmay include fluorine-containing precursors, to remove exposed regions ofsilicon oxide from silicon surfaces. By utilizing non-liquid materials,the effect on substrate features may be minimized. The term “dry” withrespect to etching may be utilized to mean that liquid water may not beused in the operations, unlike with wet etches in which water may beused as a diluent or component, such as with DHF.

Although the remaining disclosure will routinely identify specificetching processes utilizing the disclosed technology, it will be readilyunderstood that the systems and methods are equally applicable todeposition and cleaning processes as may occur in the describedchambers. Accordingly, the technology should not be considered to be solimited as for use with etching processes or chambers alone. Moreover,although an exemplary chamber is described to provide foundation for thepresent technology, it is to be understood that the present technologycan be applied to virtually any semiconductor processing chamber thatmay allow the operations described.

FIG. 1 shows a top plan view of one embodiment of a processing system100 of deposition, etching, baking, and curing chambers according toembodiments. In the figure, a pair of front opening unified pods (FOUPs)102 supply substrates of a variety of sizes that are received by roboticarms 104 and placed into a low pressure holding area 106 before beingplaced into one of the substrate processing chambers 108 a-f, positionedin tandem sections 109 a-c. A second robotic arm 110 may be used totransport the substrate wafers from the holding area 106 to thesubstrate processing chambers 108 a-f and back. Each substrateprocessing chamber 108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation, and othersubstrate processes.

The substrate processing chambers 108 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricfilm on the substrate wafer. In one configuration, two pairs of theprocessing chambers, e.g., 108 c-d and 108 e-f, may be used to depositdielectric material on the substrate, and the third pair of processingchambers, e.g., 108 a-b, may be used to etch the deposited dielectric.In another configuration, all three pairs of chambers, e.g., 108 a-f,may be configured to etch a dielectric film on the substrate. Any one ormore of the processes described may be carried out in chamber(s)separated from the fabrication system shown in different embodiments. Itwill be appreciated that additional configurations of deposition,etching, annealing, and curing chambers for dielectric films arecontemplated by system 100.

FIG. 2A shows a cross-sectional view of an exemplary process chambersystem 200 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., titanium nitride,tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, siliconnitride, silicon oxynitride, silicon oxycarbide, etc., a process gas maybe flowed into the first plasma region 215 through a gas inlet assembly205. A remote plasma system (RPS) 201 may optionally be included in thesystem, and may process a first gas which then travels through gas inletassembly 205. The inlet assembly 205 may include two or more distinctgas supply channels where the second channel (not shown) may bypass theRPS 201, if included.

A cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225,and a substrate support 265, having a substrate 255 disposed thereon,are shown and may each be included according to embodiments. Thepedestal 265 may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate, whichmay be operated to heat and/or cool the substrate or wafer duringprocessing operations. The wafer support platter of the pedestal 265,which may comprise aluminum, ceramic, or a combination thereof, may alsobe resistively heated in order to achieve relatively high temperatures,such as from up to or about 100° C. to above or about 1100° C., using anembedded resistive heater element.

The faceplate 217 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 217 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 201, may pass through a plurality of holes, shown in FIG. 2B, infaceplate 217 for a more uniform delivery into the first plasma region215.

Exemplary configurations may include having the gas inlet assembly 205open into a gas supply region 258 partitioned from the first plasmaregion 215 by faceplate 217 so that the gases/species flow through theholes in the faceplate 217 into the first plasma region 215. Structuraland operational features may be selected to prevent significant backflowof plasma from the first plasma region 215 back into the supply region258, gas inlet assembly 205, and fluid supply system 210. The faceplate217, or a conductive top portion of the chamber, and showerhead 225 areshown with an insulating ring 220 located between the features, whichallows an AC potential to be applied to the faceplate 217 relative toshowerhead 225 and/or ion suppressor 223. The insulating ring 220 may bepositioned between the faceplate 217 and the showerhead 225 and/or ionsuppressor 223 enabling a capacitively coupled plasma (CCP) to be formedin the first plasma region. A baffle (not shown) may additionally belocated in the first plasma region 215, or otherwise coupled with gasinlet assembly 205, to affect the flow of fluid into the region throughgas inlet assembly 205.

The ion suppressor 223 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of ionically-charged species out ofthe first plasma region 215 while allowing uncharged neutral or radicalspecies to pass through the ion suppressor 223 into an activated gasdelivery region between the suppressor and the showerhead. Inembodiments, the ion suppressor 223 may comprise a perforated plate witha variety of aperture configurations. These uncharged species mayinclude highly reactive species that are transported with less reactivecarrier gas through the apertures. As noted above, the migration ofionic species through the holes may be reduced, and in some instancescompletely suppressed. Controlling the amount of ionic species passingthrough the ion suppressor 223 may advantageously provide increasedcontrol over the gas mixture brought into contact with the underlyingwafer substrate, which in turn may increase control of the depositionand/or etch characteristics of the gas mixture. For example, adjustmentsin the ion concentration of the gas mixture can significantly alter itsetch selectivity, e.g., SiNx:SiOx etch ratios, Si:SiOx etch ratios, etc.In alternative embodiments in which deposition is performed, it can alsoshift the balance of conformal-to-flowable style depositions fordielectric materials.

The plurality of apertures in the ion suppressor 223 may be configuredto control the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 223. For example, theaspect ratio of the holes, or the hole diameter to length, and/or thegeometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 223 is reduced. The holes in the ion suppressor 223 mayinclude a tapered portion that faces the plasma excitation region 215,and a cylindrical portion that faces the showerhead 225. The cylindricalportion may be shaped and dimensioned to control the flow of ionicspecies passing to the showerhead 225. An adjustable electrical bias mayalso be applied to the ion suppressor 223 as an additional means tocontrol the flow of ionic species through the suppressor.

The ion suppressor 223 may function to reduce or eliminate the amount ofionically charged species traveling from the plasma generation region tothe substrate. Uncharged neutral and radical species may still passthrough the openings in the ion suppressor to react with the substrate.It should be noted that the complete elimination of ionically chargedspecies in the reaction region surrounding the substrate may not beperformed in embodiments. In certain instances, ionic species areintended to reach the substrate in order to perform the etch and/ordeposition process. In these instances, the ion suppressor may help tocontrol the concentration of ionic species in the reaction region at alevel that assists the process.

Showerhead 225 in combination with ion suppressor 223 may allow a plasmapresent in first plasma region 215 to avoid directly exciting gases insubstrate processing region 233, while still allowing excited species totravel from chamber plasma region 215 into substrate processing region233. In this way, the chamber may be configured to prevent the plasmafrom contacting a substrate 255 being etched. This may advantageouslyprotect a variety of intricate structures and films patterned on thesubstrate, which may be damaged, dislocated, or otherwise warped ifdirectly contacted by a generated plasma. Additionally, when plasma isallowed to contact the substrate or approach the substrate level, therate at which oxide species etch may increase. Accordingly, if anexposed region of material is oxide, this material may be furtherprotected by maintaining the plasma remotely from the substrate.

The processing system may further include a power supply 240electrically coupled with the processing chamber to provide electricpower to the faceplate 217, ion suppressor 223, showerhead 225, and/orpedestal 265 to generate a plasma in the first plasma region 215 orprocessing region 233. The power supply may be configured to deliver anadjustable amount of power to the chamber depending on the processperformed. Such a configuration may allow for a tunable plasma to beused in the processes being performed. Unlike a remote plasma unit,which is often presented with on or off functionality, a tunable plasmamay be configured to deliver a specific amount of power to the plasmaregion 215. This in turn may allow development of particular plasmacharacteristics such that precursors may be dissociated in specific waysto enhance the etching profiles produced by these precursors.

A plasma may be ignited either in chamber plasma region 215 aboveshowerhead 225 or substrate processing region 233 below showerhead 225.Plasma may be present in chamber plasma region 215 to produce theradical precursors from an inflow of, for example, a fluorine-containingprecursor or other precursor. An AC voltage typically in the radiofrequency (RF) range may be applied between the conductive top portionof the processing chamber, such as faceplate 217, and showerhead 225and/or ion suppressor 223 to ignite a plasma in chamber plasma region215 during deposition. An RF power supply may generate a high RFfrequency of 13.56 MHz but may also generate other frequencies alone orin combination with the 13.56 MHz frequency.

FIG. 2B shows a detailed view 253 of the features affecting theprocessing gas distribution through faceplate 217. As shown in FIGS. 2Aand 2B, faceplate 217, cooling plate 203, and gas inlet assembly 205intersect to define a gas supply region 258 into which process gases maybe delivered from gas inlet 205. The gases may fill the gas supplyregion 258 and flow to first plasma region 215 through apertures 259 infaceplate 217. The apertures 259 may be configured to direct flow in asubstantially unidirectional manner such that process gases may flowinto processing region 233, but may be partially or fully prevented frombackflow into the gas supply region 258 after traversing the faceplate217.

The gas distribution assemblies such as showerhead 225 for use in theprocessing chamber section 200 may be referred to as dual channelshowerheads (DCSH) and are additionally detailed in the embodimentsdescribed in FIG. 3. The dual channel showerhead may provide for etchingprocesses that allow for separation of etchants outside of theprocessing region 233 to provide limited interaction with chambercomponents and each other prior to being delivered into the processingregion.

The showerhead 225 may comprise an upper plate 214 and a lower plate216. The plates may be coupled with one another to define a volume 218between the plates. The coupling of the plates may be so as to providefirst fluid channels 219 through the upper and lower plates, and secondfluid channels 221 through the lower plate 216. The formed channels maybe configured to provide fluid access from the volume 218 through thelower plate 216 via second fluid channels 221 alone, and the first fluidchannels 219 may be fluidly isolated from the volume 218 between theplates and the second fluid channels 221. The volume 218 may be fluidlyaccessible through a side of the gas distribution assembly 225.

FIG. 3 is a bottom view of a showerhead 325 for use with a processingchamber according to embodiments. Showerhead 325 may correspond with theshowerhead 225 shown in FIG. 2A. Through-holes 365, which show a view offirst fluid channels 219, may have a plurality of shapes andconfigurations in order to control and affect the flow of precursorsthrough the showerhead 225. Small holes 375, which show a view of secondfluid channels 221, may be distributed substantially evenly over thesurface of the showerhead, even amongst the through-holes 365, and mayhelp to provide more even mixing of the precursors as they exit theshowerhead than other configurations.

The chambers discussed previously may be used in performing exemplarymethods including etching methods. Turning to FIG. 4 is shown exemplaryoperations in a method 400 according to embodiments of the presenttechnology. Prior to the first operation of the method a substrate maybe processed in one or more ways before being placed within a processingregion of a chamber in which method 400 may be performed. For example,trenches, holes, or other features may be formed in a substrate, whichmay include a silicon substrate. In some embodiments the holes may beformed by reactive-ion etching, which may utilize an oxide hardmask.Reactive-ion etching may produce deep, high-aspect-ratio structures, butmay leave residue within the formed structure, that may include carbon,oxygen, or other materials. Ashing operations may be performed, althoughoxide residue materials may still remain in the formed structures. Someor all of these operations may be performed in chambers or system toolsas previously described, or may be performed in different chambers onthe same system tool, which may include the chamber in which theoperations of method 400 are performed.

The method 400 may include flowing a fluorine-containing precursor intoa remote plasma region of a semiconductor processing chamber atoperation 405. An exemplary chamber may be chamber 200 previouslydescribed, which may include one or both of the RPS unit 201 or firstplasma region 215. Either or both of these regions may be the remoteplasma region used in operation 405. A plasma may be generated withinthe remote plasma region at operation 410, which may generate plasmaeffluents of the fluorine-containing precursor. The plasma effluents maybe flowed to a processing region of the chamber at operation 415. Theplasma effluents may interact with the substrate in the processingregion, which may include a trench or other feature formed through asemiconductor substrate, which may include silicon, germanium, or anyother substrate or combination of elements as would be understood.

The substrate may include a region of exposed oxygen, which may be fromone or more sources. For example, the oxygen may be an oxygen hardmaskthat remains after trenches or other features have been formed. Theoxide may also be or include a layer of oxide that has formed fromexposure of the substrate to air. For example, when a silicon substrateis exposed to air or some other oxygen source, a thin layer of oxide mayform on the substrate. At operation 420, a hydrogen-containing precursormay be provided to the processing region along with the plasmaeffluents. The plasma effluents and hydrogen-containing precursor mayinteract with the exposed oxide to remove at least a portion of theexposed oxide at operation 425. During the removal, the relativehumidity within the processing region may be maintained below or about50%.

After a portion of the oxide has been removed at operation 425, therelative humidity within the processing region may be increased togreater than or about 50% at operation 430. While increasing therelative humidity, the plasma effluents may be continued to be flowedinto the processing region in some embodiments. An additional amount ofthe exposed oxide may then be removed at operation 435. By increasingthe relative humidity within the processing region during the removal,an additional amount of oxide may be removed that may allow additionalbenefits of the process that will be described further below.

Precursors used in the method may include a fluorine-containingprecursor or a halogen-containing precursor. An exemplaryfluorine-containing precursor may be nitrogen trifluoride (NF₃), whichmay be flowed into the remote plasma region, which may be separate from,but fluidly coupled with, the processing region. Other sources offluorine may be used in conjunction with or as replacements for thenitrogen trifluoride. In general, a fluorine-containing precursor may beflowed into the remote plasma region and the fluorine-containingprecursor may include at least one precursor selected from the group ofatomic fluorine, diatomic fluorine, nitrogen trifluoride, carbontetrafluoride, hydrogen fluoride, xenon difluoride, and various otherfluorine-containing precursors used or useful in semiconductorprocessing. The precursors may also include any number of carrier gases,which may include nitrogen, helium, argon, or other noble, inert, oruseful precursors.

The hydrogen-containing precursor may include hydrogen, a hydrocarbon,water, hydrogen peroxide, or other materials that may include hydrogenas would be understood by the skilled artisan. Additional precursorssuch as carrier gases or inert materials may be included with thesecondary precursors as well. One or more of the precursors may bypassthe remote plasma region and be flowed into additional regions of theprocessing chamber. These precursors may be mixed with the plasmaeffluents in the processing region or some other region of the chamber.For example, while the fluorine-containing precursor is flowed throughthe remote plasma region to produce fluorine-containing plasmaeffluents, the hydrogen-containing precursor may bypass the remoteplasma region. The hydrogen-containing precursor may bypass the remoteplasma region by a bypass at a top of the chamber, or may be flowed intoa separate region of the chamber, such as through a port providingaccess to the volume within the showerhead, such as showerhead 225 ofFIG. 2. The hydrogen-containing precursor may then flow into theprocessing region, where it may then mix or interact withfluorine-containing plasma effluents. In embodiments, the plasmaprocessing region may be maintained plasma free during the removaloperations. By plasma free, is meant that plasma may not be activelyformed within the processing region during the operations, althoughplasma effluents produced remotely as described earlier, may be usedduring the operations.

Additional aspects of the present technology may be further understoodwith reference to FIGS. 5A-5C. FIG. 5 shows cross-sectional views ofsubstrates being processed according to embodiments of the presenttechnology. Beginning with FIG. 5A is shown a cross-sectional view of asubstrate on which the present technology may be utilized. For example,a silicon substrate 505 may have one or more features formed or definedwithin its surface, such as trench 510 as illustrated. In embodimentsencompassed by the present technology, the trench 510 may be formed by areactive-ion etching process, although other etching processes that mayform trenches and other features are similarly encompassed. The trench510 may be a high-aspect-ratio trench as previously discussed, and mayhave an aspect ratio greater than 10, greater than 50, greater than 100,or within any of these numbers or others as deeper, narrower trenchesmay be formed.

In the exemplary situation in which reactive-ion etching may have beenused to form trench 510, an oxide hardmask 515 may be formed on asurface of the substrate 505. Additionally, residue material 520 may beformed or left within the trench 510, which may include carbon, oxygen,or other impurities from the etching. Operations of a process, such asselected operations of process 400 described previously, may beperformed to remove the exposed oxide material from the surface of thesilicon substrate 505. For example, a hydrogen-containing precursor andplasma effluents of a fluorine-containing precursor may be delivered tothe processing region to at least partially remove the oxide hardmask515 as well as the residue material 520. Because the trench 510 alongwith any other features may have high aspect ratios, the relativehumidity within the processing region may be maintained below about 50%in embodiments. By maintaining the relative humidity below about 50%,water droplets may not form along the surfaces, which may cause patterndeformation or collapse when they are dried or removed.

After the oxide hardmask 515 and the residue material 520 have beenremoved, there may be a thin film of oxide remaining. As illustrated inFIG. 5B, oxide material 525 may be present on substrate 505. Forexample, oxide material 525 may be an oxide layer present across thesilicon surface from exposure to air, or may be a remaining portion ofoxide hardmask 515. The oxide material 525 may be a thin layer of oxidethat may be less than or about 10 nm, less than or about 8 nm, less thanor about 6 nm, less than or about 5 nm, less than or about 4 nm, lessthan or about 3 nm, less than or about 2 nm, less than or about 1 nm, orless. Dry etching operations, such as discussed with relation to FIG. 4,may have difficulty in removing the oxide material 525. For example, theremaining oxide material 525 may be slightly more amorphous at theinterface between the silicon substrate 505 and the overlying oxidematerial 525. The final atomic layers of oxygen may be shared betweenthe silicon matrix and with the silicon oxide structure. In some cases,dry etching operations may be incapable of cleaving these bonds, whichmay allow residual oxygen to remain at the surface, such as with oxidematerial 525.

Dry etching operations that may include certain operations as describedwith respect to FIG. 4, may increase fluorine concentration at a surfacelevel of the substrate. When the dry etching fails to cleave the finallayers of oxygen from the silicon surface, fluorine used in the etchantmay bond or associate with the oxide material 525. When used forlower-aspect-ratio features, wet etches may not retain within thesubstrate the amount of fluorine as the dry etches, but the wet etchesmay be incapable of maintaining high-aspect-ratio features, and maycause pattern collapse due to surface tension. The residual fluorine mayact as impurities that effect device function. For example, the trenchesor features may, for example, be formed in the fabrication of memorydevices. Before the cells are formed, a relatively or substantially puresubstrate surface may be sought. Impurities may increase leakage currentfrom the device, which may in turn increase power consumption, andreduce battery life due the increased refresh rate to maintain memorydata from the leakage.

Oxide material 525 may allow a surface-level concentration of fluorinewithin the substrate to increase. The fluorine contained within orattached to the oxide material 525 may be up to or greater than anatomic percent of 8% in certain regions of the substrate, such as acenter region. A desired level of fluorine to minimize leakage currentfrom this impurity may be below or about 3%, for example. Such a levelof fluorine incorporation may be produced by wet etching, but as featuresize is reduced, wet etching may cause pattern collapse and devicefailure. The present technology, however, may utilize relative humidityand/or one or more other conditions discussed below to reduce thesurface-level concentration of fluorine below other dry etch processes.

As described previously with FIG. 4, the relative humidity within theprocessing chamber may be increased above about 50%. By increasing therelative humidity, additional oxygen material may be removed from thesilicon surface, which may remove residual fluorine that may beassociated with the oxygen. By reducing the atomic percentage offluorine, leakage current may be reduced, and device performance may beimproved. However, the inventors have additionally determined that theoperations may be performed in a series of operations that first removesa bulk portion of oxide material before the relative humidity isincreased. If the relative humidity is increased above 50% initially,certain issues may occur. At high enough relative humidity, waterdroplets may be formed on the surface of the substrate, which may thencause pattern collapse or deformation as previously explained. Even amonolayer of liquid water has been shown to produce pattern deformationor collapse.

Additionally, the oxide hardmask during removal with a dry etchant mayproduce silicon fluoride. With water, however, fluorosilicic acid may beproduced from the oxide hardmask which may cause pattern collapse due toa relatively tacky consistency. Accordingly, when an oxide hardmask isbeing removed, the operations may be performed at lower relativehumidity, such as about 25% relative humidity, for example, to removethe majority of the hardmask material. In other embodiments, therelative humidity may be maintained below or about 50%, below or about45%, below or about 40%, below or about 35%, below or about 30%, belowor about 25%, below or about 20% below or about 15%, below or about 10%,or lower. The relative humidity may also be maintained between any ofthese numbers, or at any smaller range included within these ranges.

When the remaining oxide material has been reduced sufficiently, such asbelow a threshold of a few nanometers or less, or when the etchingoperation may not remove additional oxide material, the relativehumidity may be increased above about 50%. The increased relativehumidity may allow additional oxygen to be removed, and allow fluorinethat may be associated or attached to the oxide to me removed as well.The relative humidity may be increased above or about 50% inembodiments, and may also be increased above or about 55%, above orabout 60% above or about 65%, above or about 70%, above or about 75%,above or about 80%, above or about 85%, above or about 90%, above orabout 95%, or higher, although at 100% relative humidity liquid watermay be present, which may cause pattern collapse or deformation.Accordingly, the relative humidity may be maintained below or about100%, between any of the other stated percentages, or within any smallerrange within the stated ranges.

As illustrated in FIG. 5C, the increased relative humidity may allowadditional oxide material 525 to be removed from substrate 505, whichmay allow the removal of incorporated fluorine. The present technologymay similarly be used to remove thin layers of oxygen or oxide that maybe on a substrate, such as from air exposure, without the operations forremoving the hardmask material. For example, a substantially cleansubstrate that may have been exposed to air may have certain operationsof method 400 performed to further clean the substrate prior toadditional processing, such as beginning with a substrate similar tothat illustrated in FIG. 5B.

Turning to FIG. 6 is shown a chart illustrating surface concentrationsof elements in relation to relative humidity according to embodiments ofthe present technology. The chart illustrates selected operations ofmethod 400 that are performed with increasing humidity. For example, asubstrate, such as a silicon substrate, may have a thin layer of oxidematerial, such as layer 525 illustrated in FIG. 5B. Ahydrogen-containing precursor, such as water vapor, may be delivered toa processing region of a semiconductor processing chamber along withplasma effluents of a fluorine-containing precursor. FIG. 6 showsdiamonds 605, which correspond to the concentration of fluorine withinthe silicon substrate, such as within the residual oxide material at thesurface of the substrate. FIG. 6 also include squares 610, whichcorrespond to the concentration of oxygen within the silicon substrate,such as at the surface-level oxide material. As illustrated in FIG. 6,removal operations may not completely remove the oxide material.Triangles 615 illustrate the actual thickness of the residual oxidematerial on a surface of the substrate. As illustrated, the thicknessmay be less than 1 nm after hardmask removal, such as about 6 Å.

FIG. 6 also illustrates that as relative humidity is increased above25%, the fluorine concentration slightly reduces, while the oxygenconcentration and oxide thickness are substantially maintained. However,a step-wise change occurs as the relative humidity is increased aboveabout 50% relative humidity, and the oxygen concentration, oxidethickness, and fluorine concentration are all reduced. The fluorineconcentration may be reduced below about 2%, which may provide adequatedevice quality and leakage effects. Accordingly, FIG. 6 illustrates howthe present technology utilizes increased relative humidity to reducefluorine concentration within a substrate, while maintaining features onthe surface. The devices used to produce FIG. 6 maintained criticaldimensions across the substrate, for example the high-aspect-ratiofeatures were not substantially reduced, and pattern deformation orcollapse did not occur across the substrate. In embodiments, thecritical dimensions of the substrate, such as or includinghigh-aspect-ratio feature widths, may be reduced by less than 10% inembodiments, and may be reduced by less than or about 8%, less than orabout 6%, less than or about 5%, less than or about 4%, less than orabout 3%, less than or about 2%, less than or about 1%, or may besubstantially or essentially maintained by the present technology.

Process conditions may also impact the operations performed in method400 as well as other removal methods according to the presenttechnology. Each of the operations of method 400 may be performed duringa constant temperature in embodiments, while in some embodiments thetemperature may be adjusted during different operations. For example,the substrate, pedestal, or chamber temperature during the method 400may be maintained below or about 50° C. in embodiments. The substratetemperature may also be maintained below or about 45° C., below or about40° C., below or about 35° C., below or about 30° C., below or about 25°C., below or about 20° C., below or about 15° C., below or about 10° C.,below or about 5° C., below or about 0° C., below or about −5° C., orlower. In some embodiments, however, the temperature may be maintainedabove or about 0° C. to prevent the hydrogen-containing precursor, whichmay be water, from freezing. The temperature may also be maintained atany temperature within these ranges, within smaller ranges encompassedby these ranges, or between any of these ranges.

In some embodiments the first removal operation 425 may be performed ata first temperature, while the additional removal operation 435 may beperformed at a second temperature. Either or both of the temperaturesmay be within any of the ranges previously described. The secondtemperature may be lower than the first temperature in embodiments. Forexample, during the relative humidity increase, the temperature of thesubstrate may be lowered from the first temperature to the secondtemperature. By lowering the temperature of the substrate, the relativehumidity at the wafer level may also be increased without addingsubstantially more water vapor to the processing chamber. Theopportunity for water droplets to form on the chamber components or onthe substrate may then be reduced, which may aid in reducing orpreventing pattern deformation or collapse.

For example, the first temperature may be greater than or about 10° C.,and the second temperature may be less than or about 10° C. inembodiments. In some embodiments, the first temperature may be betweenabout 10° C. and about 20° C., between about 11° C. and about 18° C.,between about 12° C. and about 15° C., or may be about 12° C., about 13°C., about 14° C., or about 15° C. in embodiments. Additionally, inembodiments the second temperature may be between about 0° C. and about10° C., between about 1° C. and about 8° C., between about 2° C. andabout 5° C., or may be about 2° C., about 3° C., about 4° C., or about5° C. in embodiments. The temperature reduction between the firsttemperature and the second temperature may be at least about 2° C. inembodiments, and may be at least or about 3° C., at least or about 4°C., at least or about 5° C., at least or about 6° C., at least or about7° C., at least or about 8° C., at least or about 9° C., at least orabout 10° C., at least or about 11° C., at least or about 12° C., ormore. Additionally, the temperature decrease may be less than or about15° C., or any smaller range between any of these ranges or within anyof these ranges.

The pressure within the chamber may also affect the operationsperformed, and in embodiments the chamber pressure may be maintainedbelow about 50 Torr, below or about 40 Torr, below or about 30 Torr,below or about 25 Torr, below or about 20 Torr, below or about 15 Torr,below or about 10 Torr, below or about 5 Torr, below or about 1 Torr, orless. The pressure may also be maintained at any pressure within theseranges, within smaller ranges encompassed by these ranges, or betweenany of these ranges.

In some embodiments the first removal operation 425 may be performed ata first pressure, while the additional removal operation 435 may beperformed at a second pressure. Either or both of the pressures may bewithin any of the ranges previously described. The second pressure maybe higher than the first pressure in embodiments. For example, duringthe relative humidity increase, the pressure within the processingchamber may be increased from the first pressure to the second pressure.By increasing the pressure within the chamber, the relative humidity atthe wafer level may also be increased without adding substantially morewater vapor to the processing chamber. The opportunity for waterdroplets to form on the chamber components or on the substrate may thenbe reduced, which again may aid in reducing or preventing patterndeformation or collapse.

For example, the first pressure may be less than or about 10 Torr, andthe second pressure may be greater than or about 10 Torr in embodiments.In some embodiments, the first pressure may be between about 0 Torr andabout 10 Torr, between about 3 Torr and about 9 Torr, between about 5Torr and about 8 Torr, or may be about 5 Torr, about 6 Torr, about 7Torr, or about 8 Torr in embodiments. In embodiments, the secondpressure may be between about 10 Torr and about 20 Torr, between about10 Torr and about 18 Torr, between about 11 Torr and about 15 Torr, ormay be about 11 Torr, about 12 Torr, about 13 Torr, about 14 Torr, orabout 15 Torr. The pressure increase between the first pressure and thesecond pressure may be at least about 1 Torr in embodiments, and may beat least or about 2 Torr, at least or about 3 Torr, at least or about 4Torr, at least or about 5 Torr, at least or about 6 Torr, at least orabout 7 Torr, at least or about 8 Torr, or more in embodiments. Thepressure increase may be less than or about 10 Torr in embodiments, ormay be a smaller range within any of these ranges or between any ofthese ranges.

The flow rates of one or more of the precursors may also be adjustedwith any of the other processing conditions. For example, a flow rate ofthe fluorine-containing precursor may be reduced while increasing therelative humidity within the processing region, although in someembodiments it may be maintained or increased. During any of theoperations of method 400, the flow rate of the fluorine-containingprecursor may be between about 2 sccm and about 100 sccm. Additionally,the flow rate of the fluorine-containing precursor may be at least orabout 2 sccm, at least or about 3 sccm, at least or about 4 sccm, atleast or about 5 sccm, at least or about 6 sccm, at least or about 7sccm, at least or about 8 sccm, at least or about 9 sccm, at least orabout 10 sccm, at least or about 11 sccm, at least or about 12 sccm, atleast or about 13 sccm, at least or about 14 sccm, at least or about 15sccm, at least or about 16 sccm, at least or about 17 sccm, at least orabout 18 sccm, at least or about 19 sccm, at least or about 20 sccm, atleast or about 25 sccm, at least or about 30 sccm, at least or about 40sccm, at least or about 50 sccm, at least or about 60 sccm, at least orabout 80 sccm, or more. The flow rate may also be between any of thesestated flow rates, or within smaller ranges encompassed by any of thesenumbers.

The hydrogen-containing precursor may be flowed at any of these flowrates depending on the precursor used, which may be any number ofhydrogen-containing precursors. For example, if water vapor is utilized,the water may be introduced at a rate of at least or about 1 g/min. Thewater may also be introduced at a rate of at least or about 2 g/min, atleast or about 3 g/min, at least or about 4 g/min, at least or about 5g/min, at least or about 6 g/min, at least or about 7 g/min, at least orabout 8 g/min, at least or about 9 g/min, or more, although the watermay be introduced below about 10 g/min to reduce water condensation oncomponents and the substrate. The water may also be introduced at a flowrate between any of these stated flow rates, or within smaller rangesencompassed by any of these numbers.

At the completion of method 400, a concentration of fluorine in thesubstrate may be below or about 8% in embodiments, and may be below orabout 7%, below or about 6%, below or about 5%, below or about 4%, belowor about 3%, below or about 2%, below or about 1%, or less. Similarly, aconcentration of oxygen in the substrate may be below or about 15% inembodiments, and may be below or about 12%, below or about 10%, below orabout 9%, below or about 8%, below or about 7%, below or about 6%, belowor about 5%, below or about 4%, below or about 3%, below or about 2%,below or about 1%, or less.

The increase in relative humidity may be performed incrementally in someembodiments. For example, the relative humidity may be increased acertain percentage while the precursors are delivered to the processingregion. The relative humidity may be increased in one or more incrementsthat may be less than or about 50% relative humidity, less than or about40% relative humidity, less than or about 30% relative humidity, lessthan or about 20% relative humidity, less than or about 15% relativehumidity, less than or about 10% relative humidity, less than or about5% relative humidity, or less. The relative humidity may also beincreased in increments between any of these values or within smallerranges encompassed by any of these ranges. Additionally, the relativehumidity may be gradually increased from a starting relative humidity toa final relative humidity in embodiments that may be performed over aperiod of time to reduce the opportunity for excessive watercondensation to occur, which may lead to pattern deformation orcollapse.

Turning to FIG. 7 is shown exemplary operations in a method 700according to embodiments of the present technology. Method 700 mayinclude some or all of the operations, conditions, parameters, orresults of method 400 described previously. For example, method 700 mayinclude flowing a fluorine-containing precursor into a remote plasmaregion of a semiconductor processing chamber at operation 705. Theprecursor may be flowed while forming a plasma within the remote plasmaregion to generate plasma effluents of the fluorine-containingprecursor. The plasma effluents may be flowed into a processing regionof the chamber at operation 710. A substrate may be housed within theprocessing region, and the substrate may be characterized by ahigh-aspect-ratio feature having a region of exposed oxide.

While the plasma effluents are being flowed into the processing region,a hydrogen-containing precursor may be flowed into the processing regionat operation 715. The hydrogen-containing precursor may bypass theremote plasma region in embodiments. At operation 720 at least a portionof the exposed oxide may be removed while maintaining a relativehumidity within the processing region at greater than or about 50%. Atoperation 725, subsequent the at least partial removal, a flow rate ofthe fluorine-containing precursor may be increased while maintaining therelative humidity within the processing region at greater than or about50%. Additional exposed oxide may be removed at operation 730.

The present technology may also be effective at producing the benefitsdescribed previously in conditions where the relative humidity may notbe capable of increase above a threshold value. Additionally, inconjunction with the increase in relative humidity, the flow rate of thefluorine-containing precursor may be increased, which may further removeadditional oxygen or fluorine materials. The method may include athreshold relative humidity value, such as at least about 50% relativehumidity in order to provide the removal of materials as previouslydescribed. When the relative humidity is reduced below or about 50% fora residual oxide layer, bonds may be more difficult or incapable ofcleaving as discussed above.

FIG. 8 shows a chart illustrating surface concentrations of elements inrelation to precursor flow rate according to embodiments of the presenttechnology. The chart illustrates the effect on the incorporation ofoxygen and fluorine in a silicon substrate during operations of thepresent technology in which the fluorine-containing precursor flow ratewas increased. The relative humidity during the operations wasmaintained between about 50% and about 65%. As illustrated, the fluorineconcentration was maintained below about 3% incorporation while thefluorine-containing precursor flow rate was increased, as illustrated bysquares 805. As the flow rate was increased, the thickness of the oxidelayer previously discussed was reduced in thickness by over one Angstromas illustrated by triangles 815. Additionally, the oxygen incorporation,as illustrated by diamonds 810, was reduced with increasing flow rate.The flow rate of the fluorine-containing precursor may be any of theprecursor flow rates previously discussed both before and after theincrease. In embodiments, the flow rate may be increased at least orabout 1 sccm, at least or about 2 sccm, at least or about 3 sccm, atleast or about 4 sccm, at least or about 5 sccm, at least or about 6sccm, at least or about 7 sccm, at least or about 8 sccm, at least orabout 9 sccm, at least or about 10 sccm, at least or about 11 sccm, atleast or about 12 sccm, at least or about 13 sccm, at least or about 14sccm, at least or about 15 sccm, at least or about 20 sccm, or more.

The removal operations may reduce the oxygen incorporation below about14% in embodiments, and may lower the oxygen incorporation below orabout 12%, below or about 10%, below or about 7%, below or about 6%,below or about 5%, below or about 4%, below or about 3%, below or about2%, or less. The removal operations may also reduce the oxygenincorporation by at least or about 2%, and may reduce the oxygenincorporation by at least or about 3%, at least or about 4%, at least orabout 5%, at least or about 6%, at least or about 7%, at least or about8%, at least or about 9%, at least or about 10%, at least or about 11%,at least or about 12%, or more.

Method 700 may be performed on an oxide material, such as oxide material525 as illustrated in FIG. 5B. The exposed region of oxide may becharacterized by a thickness of less than or about 5 nm in embodiments,and may be characterized by a thickness of less than or about 4 nm, lessthan or about 3 nm, less than or about 2 nm, less than or about 1 nm,less than or about 9 Å, less than or about 8 Å, less than or about 7 Å,less than or about 6 Å, less than or about 5 Å, less than or about 4 Å,less than or about 3 Å, or less. By performing the operations on anoxide material characterized by a thickness less than or about a fewnanometers, the effects of fluorosilicic acid may be reduced, which mayreduce pattern deformation or collapse. Additionally, method 700 maymaintain or limit the effect on substrate feature dimensions orsubstrate critical dimensions, which may be reduced by less than orabout 5%, less than or about 4%, less than or about 3%, less than orabout 2%, less than or about 1%, or may be substantially or essentiallymaintained by the method.

FIG. 9 shows exemplary operations in a method 900 according toembodiments of the present technology. Method 900 may include some orall of the operations, conditions, parameters, or results of method 400or method 700 described previously. Method 900 may be performed on aresidual oxide material as discussed above with regard to method 700 ormethod 400. For example, method 900 may include flowing afluorine-containing precursor into a remote plasma region of asemiconductor processing chamber at operation 905. The precursor may beflowed while forming a plasma within the remote plasma region togenerate plasma effluents of the fluorine-containing precursor atoperation 910. The plasma effluents may be flowed into a processingregion of the chamber at operation 915. A substrate may be housed withinthe processing region, and the substrate may be characterized by ahigh-aspect-ratio feature having a region of exposed oxide.

While the plasma effluents are being flowed into the processing region,a hydrogen-containing precursor may be flowed into the processing regionat operation 920. The hydrogen-containing precursor may bypass theremote plasma region in embodiments. At operation 925 the precursors maybe continuously flowed through the processing region for a period oftime. At least a portion of the exposed oxide material may be removedduring the precursor introduction at operation 930. During the removal,the relative humidity within the processing chamber may be maintained atgreater than or about 50% as a threshold as described above.

Method 900 may also be effective at producing the benefits describedpreviously in conditions where the relative humidity may not be capableof increase above a threshold value. Additionally, in conjunction withthe increase in relative humidity and/or with an increase influorine-containing precursor flow rate, removal of oxide material maybe performed over a period of time to further reduce the oxygenconcentration at the substrate.

FIG. 10 shows a chart illustrating surface concentrations of elements inrelation to elapsed time according to embodiments of the presenttechnology. The fluorine-containing plasma effluents and thehydrogen-containing precursor were provided to the patterned substratefor a period of time as illustrated up to 400 seconds. The relativehumidity during the operations was maintained between about 50% andabout 65%. As illustrated, the method relatively maintained the fluorineconcentration, while reducing the oxygen concentration in the substrate.The fluorine incorporation is shown by squares 1005, and the oxygenincorporation is shown by diamonds 1010. The chart additionally shows areduction in residual oxide thickness with triangles 1015. Asillustrated, the removal operations of method 900 may reduce the oxygenincorporation by at least or about 1%, and may reduce the oxygenincorporation by at least or about 2%, at least or about 3%, at least orabout 4%, at least or about 5%, at least or about 6%, or more. Thedelivery of precursors and plasma effluents may be continued for atleast or about 100 seconds in embodiments, and may be continued for atleast or about 150 seconds, at least or about 200 seconds, at least orabout 250 seconds, at least or about 300 seconds, at least or about 350seconds, at least or about 400 seconds, at least or about 450 seconds,at least or about 500 seconds, or longer. As the time is increased,however, surface defects may be produced in the substrate, and mayreduce surface uniformity on the substrate. Accordingly, in someembodiments the operations may be performed for less than or about 500seconds.

The previously discussed methods may allow the removal of oxide materialfrom a substrate while limiting the fluorine incorporation, and whilemaintaining critical dimensions of the substrate features, which may behigh-aspect-ratio features. The operations performed may include one ormore of increasing the relative humidity during the removal, increasingthe fluorine-containing precursor flow rate during the removal, orcontinuing the removal for a period of time as discussed. Additionalchamber operations may also be adjusted as discussed throughout thepresent disclosure. By utilizing the present methods and operations,high-aspect-ratio features may be cleaned or etched while not causingpattern collapse unlike wet etching, and while not increasing or whilelimiting impurity inclusion such as fluorine, unlike some conventionaldry etching.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology. Additionally, methods orprocesses may be described as sequential or in steps, but it is to beunderstood that the operations may be performed concurrently, or indifferent orders than listed.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a precursor” includes aplurality of such precursors, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

The invention claimed is:
 1. An etching method comprising: flowing afluorine-containing precursor into a remote plasma region of asemiconductor processing chamber; forming a plasma within the remoteplasma region to generate plasma effluents of the fluorine-containingprecursor; flowing the plasma effluents into a processing region of thesemiconductor processing chamber, wherein the processing region houses asubstrate comprising a region of exposed oxide; providing ahydrogen-containing precursor to the processing region; removing atleast a portion of the exposed oxide while maintaining a relativehumidity within the processing region below about 50%; subsequent theremoving at least a portion of the exposed oxide, increasing therelative humidity within the processing region to greater than or about50%; and removing an additional amount of the exposed oxide.
 2. Theetching method of claim 1, further comprising continuing to flow theplasma effluents into the processing region while increasing therelative humidity within the processing region.
 3. The etching method ofclaim 2, wherein a flow rate of the plasma effluents is reduced whileincreasing the relative humidity within the processing region.
 4. Theetching method of claim 1, further comprising reducing a temperature ofthe substrate while increasing the relative humidity within theprocessing region.
 5. The etching method of claim 4, wherein thetemperature is reduced by at least about 5° C.
 6. The etching method ofclaim 1, further comprising increasing a pressure within the processingchamber while increasing the relative humidity within the processingregion.
 7. The etching method of claim 6, wherein the pressure isincreased by at least about 1 Torr.
 8. The etching method of claim 1,wherein the relative humidity is increased above about 65%.
 9. Theetching method of claim 1, wherein after the additional amount ofexposed oxide is removed, a concentration of fluorine in the substrateis below or about 5%.
 10. The etching method of claim 1, wherein afterthe additional amount of exposed oxide is removed, a concentration ofoxygen in the substrate is below or about 8%.
 11. The etching method ofclaim 1, wherein the hydrogen-containing precursor bypasses the remoteplasma region when provided to the processing region.
 12. The etchingmethod of claim 1, wherein the processing region is maintained plasmafree during the removing operations.
 13. The etching method of claim 1,wherein the relative humidity is increased incrementally by less than orabout 20% per increment.
 14. A cleaning method comprising: flowing afluorine-containing precursor into a remote plasma region of asemiconductor processing chamber while forming a plasma within theremote plasma region to generate plasma effluents of thefluorine-containing precursor; flowing the plasma effluents into aprocessing region of the semiconductor processing chamber, wherein theprocessing region houses a substrate comprising a high-aspect-ratiofeature having a region of exposed oxide; while flowing the plasmaeffluents into the processing region, providing a hydrogen-containingprecursor to the processing region; removing at least a portion of theexposed oxide while maintaining a relative humidity within theprocessing region at greater than or about 50%; subsequent the removingat least a portion of the exposed oxide, increasing a flow rate of thefluorine-containing precursor while maintaining the relative humiditywithin the processing region at greater than or about 50%; and removingan additional amount of the exposed oxide.
 15. The cleaning method ofclaim 14, wherein removing an additional amount of the exposed oxidelowers a concentration of oxygen by at least about 5%.
 16. The cleaningmethod of claim 14, wherein the flow rate of the fluorine-containingprecursor is increased by at least about 2 sccm.
 17. The cleaning methodof claim 14, wherein a thickness of the exposed region of oxide prior tothe removal operations is less than or about 2 nm.
 18. The cleaningmethod of claim 14, wherein a critical dimension of thehigh-aspect-ratio feature is reduced by less than or about 1%.
 19. Aremoval method comprising: flowing a fluorine-containing precursor intoa remote plasma region of a semiconductor processing chamber whileforming a plasma within the remote plasma region to generate plasmaeffluents of the fluorine-containing precursor; flowing the plasmaeffluents into a processing region of the semiconductor processingchamber, wherein the processing region houses a substrate comprising ahigh-aspect-ratio feature having a region of exposed oxide; whileflowing the plasma effluents into the processing region, providing ahydrogen-containing precursor to the processing region; continuing toflow the plasma effluents and the hydrogen-containing precursor into theprocessing region for at least about 200 seconds; and removing at leasta portion of the exposed oxide while maintaining a relative humiditywithin the processing region at greater than or about 50%.
 20. Theremoval method of claim 19, wherein the removing operation reduces aconcentration of oxygen within the substrate by at least about 3%.